1. Field of the Invention
The present invention relates to an antibacterial composition and a method for preparing the antibacterial composition.
2. Description of the Related Art
As various synthetic resin products have been used more frequently in recent years, contamination of the surface of synthetic resin products with bacteria has become a problem when they are utilized in the fields which require the care about hygiene, such as in the field of kitchen utensils. Bacteria and fungi may grow on the surface of caulking materials utilized for interior material in the field of architecture and may cause problems in hygiene or in appearance and so on.
In order to cope with these problems, an antibacterial and antifungal composition has been mixed with a synthetic resin for the purpose of exuding the composition from the resin thereby to provide an antibacterial and antifungal properties on the surface of the resin.
Further, in order to obtain an antibacterial and antifungal effect on the surface of the resin and its surroundings by facilitating the exudation of the antibacterial and antifungal composition from the synthetic resin, an organic antibacterial and antifungal material such as thiabendazole or the like is used.
It is also known that terpene compounds among plant extracts have an antibacterial effect. For instance, there is already known a refrigerator or an air refresher (or cleaner) that is equipped with an antifungal deodorant unit comprising phytontid obtained from a plant.
It is also known an example of providing the synthetic resin products with an antibacterial effect by incorporating a certain kind of antibacterial agent of a silver salt into the resin product.
The above-mentioned organic antibacterial and antifungal agents have however disadvantages in the following points. First, because of its volatility, the surrounding environment of the synthetic resin product will be polluted when the organic antibacterial and antifungal agents are incorporated in the synthetic resin products. Further, waste water or other fluid which had been contacted with the surface of the synthetic resin products becomes to contain the antibacterial and antifungal agent. Drainage or other fluid would become a cause for a sewage pollution which in turn would seriously influence activated sludge during effluent treatment in a sewage treatment plant.
Further, many of the substances existing in the plants described above are aromatic and volatile. It is therefore impossible to incorporate these substance in the synthetic resin product, because these substances volatilize at heating when mixed with heated and melted resin for molding.
On the other hand, the silver salt antibacterial agents have a disadvantage that silver ion of the agents would be allowed to react with chloride ion in tap water to form insoluble silver chloride, resulting in a loss of its antibacterial effect. Further, the silver salts which have a high photochemical reactivity suffer another disadvantage that they become black and deteriorate their antibacterial performance by being converted into metal silver or silver oxide. In addition, the silver salt antibacterial agents have a further disadvantage that in case of incorporating them in the resin by kneading or compounding and the resin is molded at a heating temperature of 200.degree. C. or above, it is difficult to obtain a white or transparent resin molded product because the antibacterial agents may sometimes discolor or make a dull color at the heating temperature during the molding process.